EZ-EFI Fuel Injection System - Fueling The Fire

We Put FAST's New EZ-EFI Fuel Injection System To The Test.

Most of us with classic Chevys strive to upgrade our rides for the street. We ditch drum brakes for discs, bolt in overdrive transmissions, add air conditioning, and perform a plethora of other upgrades with one goal in mind: better street manners. We've gotten used to modern cars and while we still dig the timeless lines and "soul" of our older cars, we also appreciate the technological advances of the last 40 years. One of the biggest advances in terms of drivability is electronic fuel injection, more commonly referred to as EFI.

2/20

Until recently, the only downside to slapping an EFI system into a classic Chevy was complexity, and to some degree, cost. Typically, the intake manifold had to be modified to accept fuel injectors or outright replaced. The tuning systems were complicated and either required a laptop or "one size fits most" programming. FAST saw an opening in the market for a simple to install kit and developed its EZ-EFI system. Unlike its more robust systems, like the XFI line, EZ-EFI is geared towards the "average Joe" who is more concerned with making his ride nicer to drive on the street and cruise down the highway than building a racecar.

To get the price and complexity down, the EZ-EFI system was designed to use an existing 4150-style intake manifold. The four fuel injectors are integrated into the throttle body so there's no need to buy a new intake or modify an existing one. In fact you can even use your current carb-style air cleaner. The downside to this is that with only four fuel injectors the EZ-EFI isn't really suited for engines that put out over 550 hp. Then again, contrary to what you may read on the internet, the vast majority of cars out there make under 500 ponies.

3/20

There are several features built into the EZ-EFI system to improve drivability. The key one is what FAST calls "adaptive learning." This in essence lets the system tune itself and anyone who has messed with a more complicated EFI system can certainly see the benefits. The system also has a "pre-squirt" feature that helps starting by injecting a small amount of fuel into the manifold at key-on. We found the result of this to be that our big-block fired up at the push of a button, just like a modern LS engine.

So, what this new system is all about is drivability and ease of install. To put the EZ-EFI to the test we decided to find a carbureted engine and see how easy it was to put on the FAST system and get it running good. Doing this on an engine dyno would give us better control and allow us see what the real world results would be. After all, the "butt-o-meter" is only so accurate.

MORE PHOTOS

VIEW FULL GALLERY

xclose

EZ-EFI Fuel Injection System - Fueling The Fire

Here's our baseline engine, a 454 big-block with RHS heads and a middle-of-the-road camshaft. It's one of Westech Performance's test mules so it was perfect for this exercise. Normally it makes less than 550 hp, well under the EZ-EFI's performance ceiling.

Here's the main player in the FAST EZ-EFI kit, the throttle body. One key to it carrying the "EZ" moniker is that the four fuel injectors and most of the sensors are all integrated into the throttle body. It's also compatible with any standard carb-style air cleaner, so you can keep that "old school" look.

On the back of the throttle body is the Idle air control motor along with two of the fuel injectors. The base of the throttle body also houses three manifold vacuum ports, and there's one ported vacuum port on the body near the air temperature sensor. FAST really worked hard to make the unit as compact and unobtrusive as possible.

Since the throttle body is designed to replace any carburetor that works on a 4150 square-flange manifold, it was a no brainer for FAST to make the unit accept any Holley-style throttle linkage. Just like a carb, you'll want to make sure to use a throttle return spring or two. Also, just below the braided crossover fuel line is the TPS idle re-calibration screw.

On the passenger side of the unit, there's the air temp sensor and the throttle position sensor.

Meet the brains of the system, the ECU. When connected to the wiring harness, the ECU is water tight and can be mounted just about anywhere. FAST recommends that the ECU be mounted at least a couple of feet away from any "noisy" components such as ignition boxes, coils, or distributors. There's also a red LED near the logo that will flash if the ECU detects a problem.

Also included in the kit is a wideband oxygen sensor and a bung for the exhaust system. The fitting needs to be welded, but if you can't do it yourself any competent exhaust shop can install it for few bucks. Run the supplied plug in the hole until you have the system installed and not the sensor itself. Running the O2 sensor without it being connected will shorten its life due to deposits building up.

The wiring harness may look like a bowl of spaghetti, but it's surprisingly easy to install. One reason for this is that all the connectors are clearly labeled, and FAST includes several wiring diagrams to make installation a snap.

One sensor not integrated into the throttle body is the coolant temperature sensor. It can go just about anywhere, but we chose to mount it in the intake manifold using the supplied adapter.

And with that, the system was installed and we were ready to fire up the 454 to start the calibration process. In regards to fuel our Superflow 902 dyno already has an EFI-ready system. If you're converting from a carb you will need an electric pump and regulator capable of putting out 43 psi. To make things easier, FAST does offer a fuel pump and a line kit just for the EZ-EFI system.

Set up and tuning of the EZ-EFI is done through this handheld interface. It has a straightforward menu system that we found very easy to navigate. In addition to setting up the system, it also serves as a scan tool that displays live data and diagnostic information.

The first step was to fire up the engine and let it warm up to the target temperature of 140-plus degrees. During this process we adjusted the throttle to maintain idle. We also had to input the engine size, fuel pressure, and a few other pieces of information. This was all done in a step-by-step process using the menu's "setup wizard" function. The main menu also tracks live data, reads error codes, and let us perform advanced functions.

Under the Advanced Options screen, we set our target idle speed, rev limiter and put in our air/fuel ratio targets. The rev limiter works by disabling the fuel injectors until the rpm drops to a safe level. According to FAST, this can also be used as a form of "valet mode" since it's easy to temporarily lower the RPM level.

In our application, the guys at Westech went with 14:1 at idle, 13.8:1 at cruise, and 12.8:1 at wide open throttle (WOT). During the course of the day, these were adjusted a bit since it takes a bit of experimenting to find just the right setting. For example, when cruising a leaner target (higher number) will use less fuel and increase mileage- just remember not to let the system go too lean.

The key to the FAST EZ-EFI system is its adaptive learning feature. This system goes beyond normal closed loop fuel control. In essence it tunes itself by using oxygen sensor feedback to adjust the underlying base fuel table as well as the instantaneous fueling. This way the closed loop system only has to make fine adjustments. We found that the system took a while to learn and the more we ran the engine the better it did. If installed in a car the best tactic would be to get the engine idling nicely and then drive around for an hour or so.

We decided to make our first baseline pulls using a 750 cfm Holley carb. Given that the EZ-EFI system is rated up to 550 hp, this seemed like a likely carb size it would replace. The best pull we got with the carb was 526 lb-ft at 3,900 rpm and 504 hp at 5,700.

Here, you can see one of our better EFI pulls compared to the earlier carb numbers. The FAST system made 532 lb-ft at 3,800 rpm and 496 hp at 5,600 rpm. In essence, it lost eight peak horsepower to the carb, but made an additional 6 pounds of twist. I guess we would call that a draw between the two. Where the EFI system excels is in terms of drivability. Where we had to crank to start the engine with the carb the same engine with the EFI system started with a push of a button.

Seeing the need for something different, Inglese, the induction gurus who know how to deliver a fuel/air mixture in style, came up with an EFI system with the classic look of an eight-pipe Weber carb setup that uses FAST's EZ-EFI electronics to manage everything. - Super Chevy Magazine » Read More